Integrins are the major cell surface receptors for extracellular matrix molecules, which play critical roles in a variety of biological processes. Focal adhesion kinase (FAK) has recently been established as a key component of the signal transduction pathways triggered by integrins. Aggregation of FAK with integrins and cytoskeletal proteins in focal contacts has been proposed to be responsible for FAK activation. Recent results from a number of different approaches have shown that integrin signaling through FAK leads to increased cell migration on fibronectin as well as potentially regulating cell proliferation and survival. J L Guan (1997 August-September), Int J Biochem Cell Biol., 29(8-9):1085-96. Interaction with integrin and focal adhesion kinase (FAK) regulates the cancer cell adhesion and invasion into extracellular matrix (ECM). In addition, phosphorylation of FAK correlates with the increase of cell motility and invasion. Adhesion and spreading of cancer cells on a variety of ECM proteins, including collagen type IV, leads to an increase in tyrosine phosphorylation and activation of FAK. H Sawai, et al. (2005), Molecular Cancer, 4:37.